Biomedical subjects

Xiang Chen

Publications and source records attributed to Xiang Chen.

46 records · Page 3Linked to original sources

PubMed2004

[Atherogenic index of plasma is associated with carotid intima-media thickness in patients with type 2 diabetes mellitus].

OBJECTIVE: To investigate the relationship of atherogenic index of plasma (AIP), an indirect indicator of LDL particle size, to carotid intima-media thickness (IMT) in patients with type 2 diabetes mellitus (T2DM) among Chinese Han nationality population. METHODS: One hundred and seventy-nine type 2 diabetic patients and 87 healthy subjects from a population of Chinese Han nationality were included. The AIP is the logarithmically transformed ratio of TG/HDL-c, which may serve as a surrogate method for assessing LDL particle size. The carotid IMT, as a surrogate continuous variable for macroangiopathy, was measured by B-mode ultrasonography in type 2 diabetic patients. The patients with T2DM were divided into three subgroups according to the IMT: IMT < or = 0.65 mm, 0.65 mm < IMT < or = 1.1 mm and IMT > 1.1 mm. The Student-t test, one-way analysis of variance, univariate and multivariate analyses were implemented. RESULTS: (1) In T2DM group the values of triglyeeride (TG) and AIP were significantly higher than those in control group respectively, and the HDL-c value of T2DM group was significantly lower than that of control group. (2) There was significant difference in the age, body mass index (BMI), waist-hip ratio (WHR), the duration of DM, triglyceride (TG), total cholesterol (TC), LDL-c, HDL-c, HbAlc, TG/HDL-c and AIP among the three subgroups; the HDL-c value was inversely related to the IMT of T2DM, and all the other risk factors were positively related to the IMT of T2DM. (3) Multivariate analysis by linear regression showed that the value of AIP was an important risk factor in the pathogenesis and progress of IMT in patients with T2DM. CONCLUSION: AIP value, an indirect indicator of LDL particle size, is an important risk factor in pathogenesis and progress of IMT in patients with T2DM.

Adult↗

PubMed2003

[Amplification of beta-catenin gene in the paraffin-embedded epidermal tissue].

OBJECTIVE: To establish a method of extracting DNA from the paraffin-embedded epidermal tissue and examine the amplification of beta-catenin gene by polymerase chain reaction (PCR) analysis. METHODS: Exon 3 of the beta-catenin gene was amplified by PCR in 14 paraffin-embedded Bowen's disease (BD) of various weight and years. RESULTS: The amplification of exon 3 of beta-catenin gene was successful in all the 10 mg and 20 mg samples, but not in the 5 mg samples. The amplification of exon 3 of beta-catenin gene was successful in 9 samples embedded within 10 years, and in only 2 of the 5 samples embedded more than 10 years. CONCLUSION: Epidermal tissue whose weight is 10 mg or more within 10 years of embedding can be used in the amplification of purpose gene by PCR.

Cytoskeletal Proteins↗

PubMed2003

Association between fasting and postprandial triglyceride levels and carotid intima-media thickness in type 2 diabetes patients.

OBJECTIVE: To investigate the association of fasting and postpiandial triglyceride with carotid intima-media thickness among type 2 diabetic patients in southeast China. METHODS: A total of 78 type 2 diabetic patients from southeast China were recruited. All the subjects underwent a standardized mixed-meal test (SMMT) and an oral glucose tolerance test. Carotid intima-media thickness (IMT) was measured by color doppler ultrasound examination. RESULTS: Postprandial triglyceride (PTG) after SMMT increased significantly in type 2 diabetic patients. The carotid IMT in patients with postprandial hypertriglyceridemia was significantly greater than that in patients with postprandial normal-triglyceridemia (0.90 mm vs 0.81 mm, P < 0.05), which remained significant after adjustment for fasting TG and HDL-c levels, and the IMT in patients with fasting hypertriglyceridemia only had tendency to increase compared to patients with fasting normal-triglyceridemia (0.87 mm vs 0.84 mm, P > 0.05). CONCLUSION: The results suggest that postprandial hypertriglyceridemia may be an independent risk factor of early atherosclerosis in type 2 diabetes.

Carotid Arteries↗

PubMed2003

[Refractive error and the intraocular pressure: findings in the Chinese eyes].

PURPOSE: To analysis the correlation between the refractive error and the intraocular pressure. METHODS: The IOP was measured in 142 eyes with noncontact tonometer. The refractive error were determined with an autorefractometer(TOPCON-7100). RESULTS: The analysis of variance showed that IOP of medium myopia is the highest, and a significant IOP difference between medium myopia and severe myopia, and IOP of patients less than 19yrs is significantly higher than patients more than 30 yrs; and there is also no significant influence of gender on patients' IOP, mean IOP(13.04 +/- 2.97) mmHg. CONCLUSION: These results suggest that when medium myopia IOP is relatively higher, or when a young patient less than 19 whose IOP is relatively higher than usual, that may mean the eye is under an unstable situation.

Adolescent↗

PubMed2003

[Decomposition of EMG signals based on combination of information diffusion theory and fuzzy neural network].

OBJECTIVE: To solve the problem of large samples and contradictory samples in EMG during high level muscle contraction. METHOD: By means of recording EMG during muscle contraction with linearly increasing force instead of constant force, basic MUAP templates were obtained with the combination of information diffusion theory and fuzzy neural network. Samples were compressed and contradictory samples were eliminated. RESULT: The method was tested by simulated and real EMG data and the results were satisfactory. CONCLUSION: This method is meaningful for decomposing NEMG at high level muscle contraction.

Computer Simulation↗

PubMed2003

[Effect of cariporide on immature rabbit heart].

OBJECTIVE: To investigate the protective effects of Cariporide on immature rabbit heart, and to search for the protective mechanism of the Na(+)/H(+) exchange inhibitor on immature rabbit hearts. METHODS: New Zealand immature rabbits were randomly divided into two groups (n = 12 in each group). The isolated rabbit heart model was involved in this study. The hearts were submitted to 60 minutes of normothermic ischemia with cardioplegia per 20 minutes of reperfusion. Group I received St. Thomas No2 as cardioprotective solution. Group II received St. Thomas No2 with addition of cariporide (10 micro mol/L). The left ventricular function was recorded, including left ventricular systolic pressure (LVSP), left ventricular dystolic pressure (LVDP), coronary artery flow (CAF), mean aortic pressure (MAP), aortic flow (AF) and dp/dt max. The levels of creatine phosphokinase (CK), lactic dehydrogenase (LDH) of coronary sinus venous solution were measured. The ventricular cardiomyocytes isolated from other 6 immature rabbit hearts were subdivided into 3 groups of each heart, which were attained by means of collagenase-perfusion. All cells were incubated with calcium fluoresence indicator Fluo-3/AM, and then the intracellular free calcium was measured under the laser scanning con-focal microscopy. The baseline was measured after isolation without anoxic/re-oxygenation. The control group received anoxic conditions for 60 minutes and re-oxygenation for 30 minutes, then was measured. The experiment group received the same conditions as control group with addition of Cariporide (1 micromol/L). RESULTS: After ischaemia/reperfusion, the percentage of recovery of myocardial function in group II was much better than group I; the LVDP, LVSP, MAP, AF, CAF and dp/dt max showed markedly better recovery in group II. The release of CK, LDH was significantly increased in Group I. After anoxic/re-oxygenation, the intracellular free calcium of isolated immature rabbit ventricular myocytes in control group increased significantly than baseline (P < 0.01); there were no significant difference of immature myocardial [Ca(2+)]i between experiment group and baseline (P > 0.05); and the experiment group myocardial [Ca(2+)]i reduced significantly than control (P < 0.01). CONCLUSIONS: Cariporide demonstrates significant cardio-protective effects for immature myocardium ischemia/reperfusion, and the protective mechanism may be due to the inhibition of the intracellular free calcium overload.

Animals↗

PubMed2002

Basigin (CD147) is expressed on melanoma cells and induces tumor cell invasion by stimulating production of matrix metalloproteinases by fibroblasts.

EMMPRIN, which is identical to human basigin (CD147), interacts with fibroblasts and stimulates expression of MMPs, which play an important role in tumor invasiveness and metastasis. In the present study, we demonstrated that coculture of basigin-expressing human MM cells with dermal fibroblasts resulted in the induction of MMP-1, MMP-2, MMP-3 and MT1-MMP production by fibroblasts and of melanoma cell invasion through a reconstituted basement membrane. Antibody to basigin inhibited both the production of MMPs by fibroblasts and the invasiveness of melanoma cells. Expression of basigin and MMPs in MM and surrounding fibroblasts was examined immunohistochemically in 28 specimens from 18 MM patients without metastasis and 10 with metastasis, to investigate whether basigin plays a role in metastasis of MM in vivo. Basigin was expressed in melanoma cells but not in fibroblasts. MM with metastasis had significantly higher basigin expression compared to MM without metastasis. There were significant differences between MMs with and without metastasis in the expression of MMPs in both melanoma cells and fibroblasts. Expression of MMPs in fibroblasts was positively correlated with expression levels of basigin. These immunohistochemic findings indicate that MMPs might be expressed in fibroblasts as well as melanoma cells concomitantly with basigin, which was expressed in melanoma cells more frequently in MM with metastasis. Basigin is highly expressed in melanoma cells and may play an important role in their invasiveness and metastasis by stimulating surrounding fibroblasts to express MMPs.

Adult↗

PubMed2002

[Study of the average FR of the MUAP's in a couple of agonist-antagonist muscles].

"Common Drive" is presented recently as a new concept used to explore the control mechanism of neuromuscular system. In this paper, the average firing rate (FR) of the motor unit action potential (MUAP) is estimated by means of decomposition technique for needle electromyographic (NEMG) signals obtained from elbow joint agonist-antagonist muscle pair with constant contraction force. The change tendency and correlation of the average FR with time are studied. The results of the experiment show that, no matter flexion or extension of the elbow joint, the average FR of both motor units(MUs) in the couple of agonist and antagonist descends with time, and the variations of their amplitude and fluctuation are highly correlated. This indicates that when two antagonist muscles are activated simultaneously to stiffen a joint, the nervous system views them as one unit and controls them in similar fashion. It also confirms the existence of "Common Drive" phenomenon at joint level.

Action Potentials↗

PubMed1999

Expression of Cx genes in liver and stomach of different embryonic stages.

AIM:To explore the relationship between the rules of Cx gene expression and cellular differentiation in organs of different embryonic stages.METHODS:A series of Cx gene serving as molecular probes and the Northern blot hybrydization were employed to study the Cx gene expression.RESULTS:Cx31,Cx31.1,Cx46 did not express while other Cx genes expressed in the embryonic liver and stomach. The Cx gene expression in the liver and stomach showed different state at different embryonic stages. The Cx gene expression had organic diversity. The expression of Cx26 gene was overlapping in the above organs. Cx43 did not express in the human liver after birth, but it expressed in the embryonic stage.CONCLUSION:The expression state of Cx genes is concordant with cellular differentiation. It might be a key candidate gene to regulate some differentiational events associated with cellular differentiation, proliferation,and morphogenesis in the early embryo.

Journal Article↗

PubMedDate not supplied

Human liver-derived cells stably modified for regulated proinsulin secretion function as bioimplants in vivo.

BACKGROUND: Insulin deficiency is currently treated with pharmacological insulin secretagogues, insulin injections or islet transplants. Secondary failure of pharmacological agents is common; insulin injections often fail to achieve euglycemic control; and islet transplants are rare. Non-beta cells capable of regulated insulin secretion in vivo could be a functional cure for diabetes. Hepatocytes are good candidates, being naturally glucose-responsive, protein-secreting cells, while the liver is positioned to receive direct nutrient signals that regulate insulin production. METHODS: Human liver-derived Chang cells were modified with a plasmid construct in which a bifunctional promoter comprising carbohydrate response elements and the human metallothionein IIA promoter controlled human proinsulin cDNA expression. Secretory responses of stable cell clones were characterized in vitro and in vivo by proinsulin radioimmunoassay. RESULTS: Transfected Chang cells secreted 5-8 pmol proinsulin/10(6) cells per 24 h in continuous passage for at least a year in response to 5-25 mM glucose and 10-90 microM zinc in vitro. Glucose and zinc synergistically increased proinsulin production by up to 30-fold. Non-glucose secretagogues were also active. Glucose transporter 2 (GLUT2) and glucokinase cDNA co-transfection enhanced glucose responsiveness. Intraperitoneally implanted Chang cells secreted proinsulin in scid and Balb/c mice. Serum proinsulin levels were further increased 1.3-fold (p<0.05) after glucose and 1.4- to 1.6-fold (p<0.005) after zinc administration in vivo. CONCLUSIONS: These results are the first to demonstrate stable proinsulin production in a human liver-derived cell line with activity in vitro and in vivo and provide a basis for engineering hepatocytes as in vivo bioimplants for future diabetes treatment.

Animals↗